SQlite在Google地圖上添加多個標記

Question

我想在地圖上繪製自定義標記。如何組織許多標記的顯示。

public class DatabaseHelper extends SQLiteOpenHelper { 

static final String TABLE = "geotable"; 

public DatabaseHelper(Context context) { 
    super(context, "myDB", null, 1); 
} 

@Override 
public void onCreate(SQLiteDatabase db) { 
    db.execSQL("create table geotable (" 
      + "id integer primary key autoincrement," 
      + "image text," 
      + "lng text," 
      + "lat text" + ");"); 
} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    db.execSQL("DROP TABLE IF EXISTS "+TABLE); 
    onCreate(db); 
} 

在第一堂課我用db創建表。然後把信息在這張表

case R.id.saveToBD: 

      cv.put("image", tex); 
      cv.put("lng", lng); 
      cv.put("lat", ltd); 
      break; 

然後我需要顯示所有標記從數據庫映射。但我在地圖上只看到一個（最後一個）標記。我如何組織一個循環？

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback { 

DatabaseHelper sqlHelper; 
SQLiteDatabase db; 
Cursor userCursor; 

private GoogleMap googleMap; 
private String imageTest; 
double lngTest, ltdTest; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_maps); 
    // Obtain the SupportMapFragment and get notified when the map is ready to be used. 
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager() 
      .findFragmentById(R.id.map); 
    mapFragment.getMapAsync(this); 
    sqlHelper = new DatabaseHelper(getApplicationContext()); 
} 

@Override 
public void onResume() { 
    super.onResume(); 
    db = sqlHelper.getReadableDatabase(); 

    userCursor = db.query("geotable", null, null, null, null, null, null); 

    if (userCursor.moveToFirst()) { 

     int imageColIndex = userCursor.getColumnIndex("image"); 
     int lngColIndex = userCursor.getColumnIndex("lng"); 
     int latlColIndex = userCursor.getColumnIndex("lat"); 

     do { 

     imageTest = userCursor.getString(imageColIndex); 
     lngTest = userCursor.getDouble(lngColIndex); 
     ltdTest = userCursor.getDouble(latlColIndex); 

     } 
      while (userCursor.moveToNext()); 
    } 

    else 
userCursor.close(); 

} 

@Override 
public void onDestroy() { 
    super.onDestroy(); 
    db.close(); 
    userCursor.close(); 
} 

@Override 
public void onMapReady(GoogleMap googleMap) { 
    googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(
      new LatLng(ltdTest, lngTest), 16)); 

    // You can customize the marker image using images bundled with 
    // your app, or dynamically generated bitmaps. 

     googleMap.addMarker(new MarkerOptions() 
       .icon(BitmapDescriptorFactory.fromPath(imageTest)) 
       .anchor(0.0f, 1.0f) // Anchors the marker on the bottom left 
       .position(new LatLng(ltdTest, lngTest))); 

} 

加ArrayList中，

 if (userCursor.moveToFirst()) { 

     int imageColIndex = userCursor.getColumnIndex("image"); 
     int lngColIndex = userCursor.getColumnIndex("lng"); 
     int latlColIndex = userCursor.getColumnIndex("lat"); 

     do { 

     imageTest = userCursor.getString(imageColIndex); 
     lngTest = userCursor.getDouble(lngColIndex); 
     ltdTest = userCursor.getDouble(latlColIndex); 

      geoList.add(imageTest); 
      geoList.add(lngTest); 
      geoList.add(ltdTest); 

     } 
      while (userCursor.moveToNext()); 
    } 

然後顯示與週期標記

 for (int i = 0; i < geoList.size(); i=i+3) { 

     googleMap.addMarker(new MarkerOptions() 
       .icon(BitmapDescriptorFactory.fromPath((String) geoList.get(i))) 
       .anchor(0.0f, 1.0f) // Anchors the marker on the bottom left 
       .position(new LatLng((Double) geoList.get(i+2), (Double) geoList.get(i+1)))); 

    } 

在地圖上只顯示最後添加到DB標誌，我'加2-10標誌但見只有最後。

Answer 1

您是從整型變量的geotable在onResume()讀取數據：在onMapReady(GoogleMap googleMap)

imageTest = userCursor.getString(imageColIndex); 
lngTest = userCursor.getDouble(lngColIndex); 
ltdTest = userCursor.getDouble(latlColIndex); 

然後您添加使用上述變量的值，其中包含的只有最後一排數據標記您的geotable：

googleMap.addMarker(new MarkerOptions() 
    .icon(BitmapDescriptorFactory.fromPath(imageTest)) 
    .anchor(0.0f, 1.0f) // Anchors the marker on the bottom left 
    .position(new LatLng(ltdTest, lngTest))); 

您應該使用ArrayList從geotable獲取數據並在onMapReady(GoogleMap googleMap)的循環內添加多個標記。